ipa: Declare the ipaCreate() function prototype

IPA modules have to implement a public ipaCreate() function, but its
prototype isn't declared in any header file. This allows for modules to
get the prototype wrong without being warned by the compiler. Fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/ipa_interface.cpp

@@ -261,6 +261,16 @@
  * \sa libcamera::IPAInterface::processEvent()
  */
 
+/**
+ * \fn ipaCreate()
+ * \brief Entry point to the IPA modules
+ *
+ * This function is the entry point to the IPA modules. It is implemented by
+ * every IPA module, and called by libcamera to create a new IPA context.
+ *
+ * \return A newly created IPA context
+ */
+
 namespace libcamera {
 
 /**